Electric water heater



May 24, 1949. wl K's 2,471,133

' ELECTRIC WATER HEATER Filed Jan. 18, 1946 GERALD C. Wncns 33 INVENTOR BYWM i ATI'ORNEY Patented May 24, 1949 -UNITED STATES PATENT OFFICE ELECTRIC WATER HEATER Gerald C. Wicks, Buenos Air-es, Argentina Application January 18, 1946, Serial No. 641,911

2 Claims. 1

lhe present invention relates to an electric Water heater, and, more particularly, to an electricwater heater of the type which can be connected to a cold water faucet to heat the water delivered from the faucet by means of an electric heating unit, such as a heating coil, disposed in a water heating compartment from which hot water is discharged in a continuous stream as long as cold water is fed to the heater.

- One object of the invention is to provide ina water heater including a heating unit in the term of an electric resistance coil, electric means for automatically breaking the circuit through the heating coil when the level of the water in the water heating compartment falls below .a predetermined height which is above the top -:of the heating coil and for automatically restoring the heating circuit when the level of the water reaches said predetermined height.

Another object of the invention is to provide an electric water heater including a heating coil in which substantially the entire heating coil remains submerged in the water to be heated whenever current flows through the coil, thus preventing an overheating of the coil.

A still further object of the invention is to arrange the water inlet and outlet passages of a continuous electric water heater in such a manner that no electric charges can be transmitted from the electric heating unit through the body of the water to conductors or semiconductors which may come in contact with the stream of water outside of the heater, so that a person touching the faucet through which the water is delivered to the heater or the stream of hot water discharged from the heater will be positively protected from electric shocks.

These and other objects, which will appear more clearly as the specification proceeds, are accomplished according to the present invention by the arrangement and combination of elements set forth in the following detailed description,

- defined in the appended claims and illustratively Fig. 4 is abottom elevational view of the upper 24 of the overflow pipe.

2 disc-shaped elementin which the water inlet passage is formed.

Referring now to the drawings, and first to Fig. 1,-l-ia and 11b are the upper and lower halves, respectively, of a substantially cylindrical container consisting of heat resisting glass and having an integral flat circular top wall [2a and an integral fiat circular bottom wall 12b. A vertical partition wall is formed in two parts 13a and 13b integral with the two halves Ha, I lb, respectively of the container to divide the latter into a larger water heating compartment and a smaller 'eontrolunit compartment [5. The'two halves I la, l lb of thecontainer are provided with outwardly projecting peripheral flanges lBa, I61) 'along their adjacent edges and are secured together with interposition of a suitably shaped gasket I?! bymeans of screws l8 passing through aligned holes in said flanges 16a, [6b and gasket H, and nuts 19 cooperating with said screws Hi.

The top wall 12a of the container is provided near its periphery with a water inlet port 20 leading into the water heating compartment I4, and

the bottom wall I2b is provided, opposite the water inlet port 20, with a similar water outlet port 2|. An overflow pipe of a flow cross-section slightly smaller than that of the inlet port 20 has its lower end 22 fitted into the outlet port 2| and includes a short horizontal portion 23 and a vertical portion 24 rising approximatel centrally of the water heating compartment H to a level just befow the upper edge of the lower half Nb of the container. The vertical pipe portion 24 is outwardly threaded and carries a nut 25. An insulating bracket (see Fig. 2) includes a lower cylindrical portion 26 provided in its two end faces with frustoconical recesses 21, 23 leaving between them a transverse web provided with an axial bore 29 traversed by the vertical portion A helical groove 30 is provided in the outer periphery of the cylindrical bracket portion 26 and a resistance heating coil 3| is mounted in the groove 30. Radial bores 32 and 33 lead from the recesses '21 and 28 to the beginning and the end, respectively, of the groove 30 to receive electric conductors connected to the opposite ends of the coil 3|. The bracket is heated with the lower surface of the transverse web on the nut 25 and is secured in position by a nut 34 screwed onto the pipe portion '24 against the upper surface of the transverse web. The

upper surface of the cylindrical bracket portion 26 is disposed at a level slightly higher than the open upper end of the pipe portion 24. Two lug shapedelements35, 36 are integral parts of the insulating bracket and project upwardly from the top of the cylindrical portion 26 thereof in diametrically opposite positions. A plate-shaped control electrode 31 is secured to one side of the lug 35 and projects across the cylindrical bracket portion 26, and a second plate shaped electrode 38 is secured to the opposite side of the lug 36 and extends parallel to said first electrode 31 at a distance from the latter corresponding to the thickness of the lugs 35, 36 which, in the example shown, is about one eighth of an inch.

The control unit compartment contains an electromagnet carried by a bracket 39 secured to the top wall |2a of the container and including a winding 46 and a pivoted armature 4|. A pair of normally open contacts 43, 44 is closed by an arm 45 of the armature 4| when the magnet is energized. The electrical connections are as follows: A first conductor 46 serves to connect one terminal of any suitable source of current (not shown) in parallel to one end of .the winding 40 -of the electromagnet and to one contact 43 of said pain A second conductor 41 serves to connect the other terminal of the source of current in parallel to the control electrode 3'! and to the upper end .of the heating coil 3|. A third conductor 48 connects the second electrode 38 with the other end of the magnet winding 40, and a fourth conductor 49 connects the second contact 44 of said pair.

with the lower end of the heating coil 3|.

The water to be heated is fed to the inlet port 20 and the hot water is discharged from the outlet port 2| through insulating passages of relatively great length by means of the following ar- I rangement: An assembly including a circular gasket 50a, 59b and a circular disc-shaped element of heat resisting glass 5|a, 5|b is applied to each of the outer flat surfaces of the top wall |2a and of the bottom wall |2b of the container. The

top assembly 50a, 5|a is secured to the top wall |2a by means of screws 52, one of which serves also to affix the bracket 39 to the top wall I202. The bottom assembly 501), 5|b is secured to the bottom wall |2b by means of screws 53 one of which passes through a plate 22a traversed by and soldered to the lower portion 22 of the overflow pipe, said plate 22a being applied to the inner surface of the bottom wall I21; and holding the overflow pipe securely in place. Each discshaped element 5|a, 5|b is provided in the flat surface thereof directed toward the adjacent wall I211, I212 of the container with a spiral groove 54, the inner end of which emerges from a central circular recess 55 formed in the disc-shaped element 1 while its outer end registers with the port 2|, 22 in the adjacent end wall l2a, |2b of the container and with a corresponding hole 56 provided in the gasket 59a, 50b interposed between the disc-shaped element 5|a, 5|b and the adjacent container wall l2a, l2b. Each disc-shaped element 5|a, 5|b is further provided with a central hole 51 opening into the recess 55 and having a smaller diameter than the latter.

An axially open inlet tube 58 having at its lower end an outwardly projecting peripheral flange fitting into the recess 55 of the upper disc-shaped element 5 la passes through the central hole 51 of this element and is provided with an external screw thread at its upper end. An outlet tube 59 closed at its lower end is seated with an outwardly projecting peripheral flange provided at its upper end in the recess 55 of the lower discshaped element fill). The lower end wall of the tube 59 is provided with a small threaded bore and its peripheral wall is formed near the lower end of the tube with a number of radial apertures 60 and with an external screw thread extending from said lower end beyond the apertured portion of the tube.

The container assembly is supported in and protected by a substantially oval sheet metal shell comprising an upper shell portion 6|a and a lower shell portion 6|b provided at their adjacent edges with overlapping peripheral flanges and secured together by a clamping ring 62 of U-cross-section. The upper shell portion 6|a is depressed at its top to form a stepped cup 63, the flat bottom of which is provided with a central aperture of a diameter substantially equal to that of the hole 51. The bottom of the cup 63 rests on an annular gasket 64 applied to the top surface of the disc-shaped element 5|a, and the tube 58 passes upwardly through the gasket and through the aperture in the bottom of the cup 63 into the latter, the parts being secured together by means of a nut 65 screwed onto the upper threaded portion of the tube 58. A flat ring 66 is soldered to the step of the cup 63 to form an inwardly projecting flange. A substantially tubular mouthpiece 6'1 of an elastic material, such as rubber, is mounted on the flange 66 and serves to connect the heater to a cold water faucet. The mouthpiece 6'! comprises a lower cylindrical portion provided with a peripheral groove, in which the flange 66 is seated, and an upwardly and outwardly projecting substantially frustoconical portion turned inwardly and downwardly upon itself at its upper edge to provide a substantially cylindrical depending lip which will apply itself with increasing force to a faucet as the pressure of water discharged from the faucet into the mouthpiece increases.

The lower shell portion 6|b is formed at its bottom with a depression having the form of a small cylindrical cup 68 turned upside down and provided with a recess along its edge. The bottom of the cup 68 rests against an annular'gasket 69 applied to the outer surface of the disc-shaped element Ella, and the tube 59 passes through a suitable central hole of the cup bottom to a plane near the outer edge of the cup 68. A nut 10 screwed on the tube 59 against the bottom of the cup 68 holds the parts together. An annular gasket H is seated in the recess at the edge of the cup 68, and the latter is closed by means of a perforated strainer and distributor plate 12 pressed in the recess to lie flush with the bottom surface of the shell portion BIZ) and secured to the tube 59 by means of a screw 13 passing through a central hole in the strainer plate 12 into the threaded bore provided in the end wall of the tube 59. A rubber venting tube 14 of small cross-section leads from the top of the heating compartment l4 into the cup 68 to prevent the formation of air or steam pockets in the upper part of compartment M.

The device operates as follows: The mouthpiece 61 is pushed onto a faucet and the two conductors 46, 41 are connected to the opposite terminals, respectively, of a source of current. When water is admitted through the faucet it will pass through the tube 58, recess 55, spiral groove 54, and openings 56 and 20 into the water heating compartment l4 and fill the latter to the level of the upper open end of the overflow pipe 24 so that the heating coil 3| is substantially submerged. At this time, no current passes through the heating coil 3| because the contacts 43, 44 are open.

Thereafter, the water continues to rise in the compartment l 4, because the flow cross-section of the overflow pipe 24 is slightly smaller than that of the inlet port 28 and the air in the upper part of compartment M can escape through tube 14. When the water has sufiiciently risen to fill at least partly the space between the two control electrodes 31, 38, an energizing circuit for the winding 40 of the electromagnet is closed through the water, as follows: Conductor 46, winding 40, conductor 48, control electrode 38, water, control electrode 31, conductor 41. The electromagnet operates and attracts its armature 4|, whereupon the arm 45 of the latter closes the contacts 43, 44 and establishes the following heating circuit: Conductor 46, contact 43, contact 44, conductor 49, heating coil 3|, conductor 41. The water surrounding the heating coil 3| is now heated and as additional cold water flows down along the peripheral wall of the heating compartment M, the hot water rises continuously in the center of the compartment and is discharged through the overflow pipe 24, 23, 22, holes 2|, 56, groove 54, recess 55, tube 59, apertures 63, cup 68 and strainer 12. Owing to the length and the small cross section of the spiral insulating paths traversed by the water in the grooves 54 before and after its contact with the exposed current carrying heating coil 3| no appreciable electric charges can be transmitted through the Water to any conductor or semiconductor outside the heater.

When the faucet is closed and the supply of cold water ceases, the level of the water in the compartment l4 begins to fall, first slowly as air enters the heating compartment I4 through the tube 14 and then more rapidly as the water boils and the steam pressure increases. When the level of the water drops below the lower edge of the electrode plates 31, 38, the energizing circuit for the electromagnet is normally interrupted and the contacts 43, 44 open, thus breaking the heating circuit. Even if the breaking of the heating circuit should be delayed for a short period of time due to the accidental presence of some conductive material between the control electrodes 31, 38, the heating coil 3| will remain substantially submerged in the water because the opening of the overflow pipe is at approximately the same level as the top portion of the heating coil 3|. However, steam rising from the boiling water tends to carry off any electro-conductive residue i which may have remained between the electrodes 31, 38 and the heating circuit will be definitely broken. The heating circuit will then remain open until the gap between the electrodes 31, 38 becomes at least partially filled again upon admission of cold water to the heater,

It should be understood that the heater can be used for the heating of electro-conductive liquids other than water.

I claim:

1. An electric water heater, including two elements of insulating material, each having a surface provided with a recess at least part of which has the shape of a tortuous groove of considerable length, a connecting member provided with two sealing surfaces of insulating material in intimate contact with the recessed surfaces of said two elements, respectively, to form a sealing cover for at least the major portions of both said tortuous grooves, said connecting member providing a passage therethrough from one end of the tortuous groove in one of said elements to one end of the tortuous groove in the other element, means for supplying water to be heated continuously to the other end of the tortuous groove of said first element end and for discharging heated water continuously from the other end of the tortuous groove of said second element, whereby said two closed tortuous grooves and said passage through said intermediate member define a flow-path for the water through the heater, and an electric heating unit disposed in said flow-path remote from the supply end and from the discharge end thereof.

2. In an electric water heater having a closed heating compartment including a flat top wall provided with an inlet port, and a flat bottom wall provided with an outlet port, and an electric heating unit in said compartment which may transmit an electric charge to the water flowing past said heating unit, the combination of two disc-shaped elements of insulating material secured in a liquid tight manner to the top and bottom walls, respectively, of said compartment, each of said disc-shaped elements being provided in its face directed toward the adjacent wall of the compartment with a spiral groove one end of which registers with the port provided in said wall while it communicates at its other end with a hole through said disc-shaped element, said compartment and said disc-shaped elements consisting of heat resisting glass.

GERALD C. WICKS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 958,846 Wood May 24, 1910 1,358,982 Papini Nov. 16, 1920 1,561,243 Keene Nov. 10, 1925 1,654,551 Muhleisen Jan. 3, 1928 1,935,247 Ludwig Nov. 14, 1933 2,032,210 Holt Feb. 25, 1936 

